Polymorphism relates to the occurrence of different crystal forms for a molecule. These different crystalline forms have distinct crystal structures and vary in physical properties like melting point and XRPD spectrum. A particular polymorph may have advantageous properties for the manufacture and use of the drug substance.
The present invention relates to a particular polymorphic form of 1-(1-methyl-1H-pyrazol-4-yl)-N-((1R,5S,7S)-9-methyl-3-oxa-9-azabicyclo[3.3.1]nonan-7-yl)-1H-indole-3-carboxamide, free base, which is an antagonist of the 5-HT3 receptor. 1-(1-Methyl-1H-pyrazol-4-yl)-N-((1R,5S,7S)-9-methyl-3-oxa-9-azabicyclo[3.3.1]nonan-7-yl)-1H-indole-3-carboxamide, 2,2,2-trifluoroacetic acid salt, is disclosed in PCT Publication No. WO 2014/014951, published Jan. 23, 2014.
The present polymorphic form, 1-(1-methyl-1H-pyrazol-4-yl)-N-((1R,5S,7S)-9-methyl-3-oxa-9-azabicyclo[3.3.1]nonan-7-yl)-1H-indole-3-carboxamide, Form G, provides an anhydrate form, that can be readily and reproducibly produced and is stable to prolonged thermal stress.